Specific heat and the cooperative Jahn-Teller effect in

Abstract

The specific heat of has been measured over the wide temperature range from 3.5 K to 200 K. Only one anomaly, indicating the phase transition driven by the cooperative Jahn-Teller effect, has been found, at . The phonon specific heat has been estimated and subtracted from the heat capacity measured. The Schottky anomaly originating from the population of the lowest two doublets of the dysprosium ions, and the -anomaly connected with the Jahn-Teller phase transition have been described theoretically using the molecular-field approximation. Satisfactory agreement between experimental points and theoretical dependences calculated using the material parameters known from the literature was obtained.